Alpine Swifts Fly Nonstop

How long can a bird fly without touching the earth? To find out, Swiss scientists attached sensors to Alpine Swifts. The sensors showed long periods when the swifts were gliding and not flapping their wings. Were the birds asleep? Scientists don’t know for sure. It could be that Alpine Swifts sleep during the summer breeding season — and don’t sleep at all during migration. But why do they stay aloft so long? Swifts can’t perch because they have very short legs. So if they can manage it, avoiding touching down makes perfect sense.

Experts have speculated for years that some kinds of swifts spend long, continuous periods of their lives in the air. To figure out exactly what they get up to, Swiss scientists began researching Alpine Swifts — a large species with a wing-span of over two feet. The research published in 2013 involved attaching sensors to some of the swifts while they were nesting in Europe, and recovering them on the birds’ return from spending winter in Africa.

[Alpine Swifts calling]

It was already known that the swifts eat on the wing. But what about sleep? The sensors showed long periods when the swifts were gliding and not flapping their wings. But scientists aren’t sure if that means the birds were asleep. It could be that, like some other animals, Alpine Swifts do all their sleeping during the summer breeding season. And don’t sleep at all during migration.

As for why they stay aloft so long — while they’re supreme fliers, swifts find landing complicated. They can’t perch because they have very short legs. So if they can manage it, avoiding touching down makes perfect sense.